Plating apparatus and plating method

ABSTRACT

A plating apparatus has an ashing unit ( 300 ) configured to perform an ashing process on a resist ( 502 ) applied on a surface of a seed layer ( 500 ) formed on a substrate (W), and a pre-wetting section ( 26 ) configured to provide hydrophilicity to a surface of the substrate after the ashing process. The plating apparatus includes a pre-soaking section ( 28 ) configured to bring the surface of the substrate into contact with a treatment solution to clean or activate a surface of the seed layer formed on the substrate. The plating apparatus also includes a plating unit ( 34 ) configured to bring the surface of the substrate into a plating solution in a plating tank while the resist is used as a mask so as to form a plated film ( 504 ) on the surface of the seed layer formed on the substrate.

TECHNICAL FIELD

The present invention relates to a plating apparatus and a platingmethod for plating a surface of a substrate, and more particularly to aplating apparatus and a plating method for forming a bump (protrudingelectrode), which provides electrical connection with an electrode of apackage or a semiconductor chip, on a surface of a semiconductor waferwhile a resist is used as a mask.

BACKGROUND ART

In tape automated bonding (TAB) or flip chip, for example, it has widelybeen practiced to form protruding connecting electrodes (bumps) of gold,copper, solder, or nickel, or a multi-layer laminate of these metals atpredetermined portions (electrodes) on a surface of a semiconductor chiphaving interconnects formed therein, and to electrically connect theinterconnects via bumps with electrodes of a package or with TABelectrodes. In order to form bumps, there have been used various methodsincluding electroplating, vapor deposition, printing, and ball bumping.In view of a recent increase in the number of I/O terminals in asemiconductor chip and a trend toward finer pitches, an electroplatingprocess has more frequently been employed because the electroplatingprocess can achieve fine processing and has relatively stableperformance.

In an electroplating process, bumps are formed at predeterminedpositions of a surface of a substrate having interconnections in thefollowing manner. In such a process, a resist has been widely used as amask. First, as shown in FIG. 1A, a seed layer 500 is deposited as afeeding layer on a surface of a substrate W by sputtering or vapordeposition. Then, a resist 502 is applied onto an overall surface of theseed layer 500 so as to have a height H of, for example, 20 to 120 μm.Thereafter, exposure and development are performed on a surface of theresist 502 to form openings 502 a having a diameter D of about 20 toabout 200 μm at predetermined positions in the resist 502. Then, asshown in FIG. 1B, a metal such as Au or Cu, which is a material forbumps, is deposited in the openings 502 a by an electroplating processso as to form and grow plated films 504 in the openings 502 a. As shownin FIG. 1C, the resist 502 is stripped and removed from the surface ofthe substrate W. Then, as shown in FIG. 1D, unnecessary portions of theseed layer 500 are etched and removed from the surface of the substrateW. Then, a reflowing process is performed, as needed, to form sphericalbumps 506 as shown in FIG. 1E.

Electroplating processes can be grouped into a jet-type or cup-typeelectroplating process, in which a plating solution is ejected upward toa substrate such as a semiconductor wafer positioned horizontally in astate such that a surface of the substrate to be plated faces downward,and a dipping-type electroplating process, in which a substrate isimmersed vertically in a plating solution within a plating tank whilethe plating solution is supplied from the bottom of the plating tank soas to overflow the plating tank. According to the dipping-typeelectroplating process, bubbles which would adversely affect qualitiesof plated substrates are readily removed, and the footprint of a platingapparatus can be reduced. Further, the dipping-type electroplatingprocess can be readily adapted to variations in wafer size. Thus, thedipping-type electroplating process is considered to be suitable for abump formation process, which fills relatively large holes and requiresa considerably long period of time to complete a plating process.

When plated films are formed in openings in a resist to form bumps on asurface of a substrate such as a semiconductor wafer, because a resistis generally made of a hydrophobic material having low wettability, aplating solution is unlikely to enter the openings in the resist.Accordingly, as shown by an imaginary line in FIG. 1A, air bubbles 508may be produced in a plating solution. Such air bubbles 508 tend toremain within the openings 502 a to cause plating defects such asinsufficient plating.

In order to prevent such plating defects, a surface-active agent may beadded to a plating solution to lower surface tension of the platingsolution so as to readily introduce the plating solution into theopenings in the resist. However, when the surface tension of the platingsolution is lowered, air bubbles are likely to be produced in theplating solution when the plating solution is circulated. Further, whena new surface-active agent is added to a plating solution, anomaly ofdeposition may occur so as to increase the amount of organic substancestrapped in the plated films. Thus, a surface-active agent may adverselyaffect properties of the plated films.

With a conventional electroplating apparatus using a dipping-typeelectroplating process, air bubbles are likely to be released from theopenings in the resist. Such an electroplating apparatus employs asubstrate holder which holds a substrate such as a semiconductor waferin a state such that a (front) surface of the substrate to be plated isexposed while sealing a peripheral edge and a rear face of thesubstrate. The substrate holder is immersed in a plating solutiontogether with the substrate to plate the surface of the substrate. Thus,according to a conventional electroplating apparatus using adipping-type electroplating process, it is difficult to automate anentire plating process from loading of a substrate to unloading of thesubstrate after a plating process.

Further, a conventional plating apparatus for bump formation generallyhas a plating section for performing a plating process, an additionalprocess section for performing additional processes incidental to theplating process, such as a cleaning process and a pre-treatment process,and a transfer robot for transferring a substrate between the platingsection and the additional process section. Openings are formed atpredetermined positions in a resist on a substrate. Substrates arehoused in a substrate cassette. One of the substrates is picked out fromthe substrate cassette. Then, a metal such as Au or Cu, which is amaterial for bumps, is deposited and grown in the openings of the resiston the substrate. Thereafter, the substrate is subjected to apost-treatment process such as a cleaning and drying process andreturned to the substrate cassette.

Substrates which have been plated by the plating apparatus and returnedto the substrate cassette are transferred to a subsequent resiststripping unit, etching unit, or the like while the substrates arehoused in the substrate cassette. In the resist stripping unit, theresist is stripped and removed from the surface of the substrate. In theetching unit, unnecessary portions of the seed layer are removed fromthe surface of the substrate.

However, the conventional plating apparatus for bump formation isdesigned to perform processes until a plating process, but not toperform processes after the plating process, in consideration ofmanufacturing lead-time suitable for mass production of a limitedvariety of goods. Accordingly, the conventional plating apparatus forbump formation cannot continuously perform a sequence of processes tocomplete bump formation. Further, the conventional plating apparatus forbump formation requires a large space for additional process units suchas a resist stripping unit and an etching unit and has less flexibilityin arrangement.

DISCLOSURE OF INVENTION

The present invention has been made in view of the above drawbacks. Itis, therefore, a first object of the present invention to provide aplating apparatus and a plating method which can introduce a platingsolution reliably into an opening in a resist applied on a surface of asubstrate without adding any surface-active agent in a plating solutionand can achieve a plating process without any plating defects such asinsufficient plating.

A second object of the present invention is to provide a platingapparatus and a plating method which can automatically form a platedfilm suitable for a protruding electrode such as a bump with adipping-type process, which can readily release air bubbles.

A third object of the present invention is to provide a platingapparatus which can continuously perform processes including a platingprocess such as a bump formation process, can reduce a space for thewhole apparatus, and is suitable for limited production of a widevariety of goods.

According to a first aspect of the present invention, there is provideda plating apparatus having an ashing unit configured to perform anashing process on a resist applied on a surface of a seed layer formedon a substrate, and a pre-wetting section configured to providehydrophilicity to a surface of the substrate after the ashing process.The plating apparatus includes a pre-soaking section configured to bringthe surface of the substrate into contact with a treatment solution toclean or activate a surface of the seed layer formed on the substrate.The plating apparatus also includes a plating unit configured to bringthe surface of the substrate into a plating solution in a plating tankwhile the resist is used as a mask so as to form a plated film on thesurface of the seed layer formed on the substrate.

When a substrate is plated while a resist is used as a mask, because theresist makes a surface of the substrate hydrophobic, the surface of thesubstrate is unlikely to be brought into contact with a plating solutionto thus cause plating defects such as insufficient plating. The ashingunit performs an ashing process on the resist applied on the surface ofthe substrate prior to the plating process. The ashing process canreform a hydrophobic surface of the resist into a hydrophilic surface.Thus, the surface of the substrate becomes likely to be brought intocontact with a plating solution. Further, a hydrophilic process may beperformed on the surface of the substrate in the pre-wetting sectionafter the ashing process to replace a gas in the openings formed in theresist with water and further replace the water with a plating solution.Thus, it is possible to prevent plating defects such as insufficientplating.

The ashing unit may be configured to apply at least one of plasma,light, and an electromagnetic wave to the resist to perform the ashingprocess on the resist. When the ashing unit is configured to applyhigh-energy light or electromagnetic waves including plasma, ultravioletrays, and far ultraviolet rays, then high-energy ions, photons, orelectrons collide with the resist to produce an active gas. The ions,photons, or electrons and the active gas can decompose and removeorganic substances such as resist residues. Hydrogen is abstracted fromorganic substances in the resist, or principal chains or side chains oforganic substances in the resist 502 are cut, to thereby removecontaminants from the surface of the substrate and reform the surface ofthe substrate. The ashing unit may be provided inside or outside of aframe of the plating apparatus.

The pre-wetting section may comprise a pre-wetting tank configured toimmerse a substrate in pure water or a pre-wetting device configured toeject pure water through a spray to a surface of the substrate. Thepre-wetting section may be substantially under vacuum or under apressure lower than an atmospheric pressure. The pre-wetting section maycomprise a deaeration device for deaerating the pure water.

The pre-wetting section may comprise a plurality of pre-wetting portionshaving different functions. For example, the plating apparatus mayinclude a dipping-type pre-wetting portion using deaerated water, aspray-type pre-wetting section, and the like. In such a case, a suitablepre-wetting portion can be selected according to a recipe. With thisarrangement, limitation on processes due to types of pre-wettingsections can be eliminated, and the plating apparatus can performvarious types of processes.

The pre-soaking section may comprise a pre-soaking tank to hold thetreatment solution including at least one of ozone water, an acidsolution, an alkali solution, an acid degreasing agent, a solutioncontaining a developer, a solution containing a resist strippingsolution, and reduced water of an electrolytic solution. For example,when the surface of the substrate is brought into contact with atreatment solution (acid solution) such as a sulfuric acid orhydrochloric acid solution, an oxide film, which has a high electricalresistance, formed on a surface of a seed layer can be etched to removethe oxide film and expose a clean metal surface of the seed layer.Further, a substrate may be treated with ozone water and then treatedwith an acid solution.

Alternatively, the pre-soaking section may comprise a pre-soaking tankto hold the treatment solution including an acid solution or an aciddegreasing agent so as to perform an electrolytic process on thesubstrate in the treatment solution in a state such that the substrateserves as a cathode.

The plating unit may comprise an anode disposed in the plating solutionand an anode weight measuring device operable to measure weight of theanode. The anode weight measuring device may comprise a load cell. Withthis arrangement, consumption of the anode can be measured moreaccurately than in a case where the weight of the anode has heretoforebeen estimated indirectly based on the amount of current supplied to theanode. Therefore, it is possible to accurately determine when the anodeshould be replaced. The weight of the anode can be measured even duringa plating process. Thus, even during a continuous plating process, it ispossible to accurately determine when the anode should be replaced.Accordingly, the plating apparatus can be operated premeditatedly.

The plating tank may comprise an anode disposed in the plating solution,a dummy anode provided in the plating tank, and a single power supplyconfigured to apply a voltage selectively to the anode for an actualplating process and to the dummy anode for a dummy plating process.Generally, a power supply which is used for dummy plating at the time ofreplacement of a plating solution is not used during a plating process.Thus, a power supply for dummy plating is not used for a long term andis provided uneconomically. With the above arrangement, a single powersupply can be switched so as to perform a dummy plating process and anactual plating process. Thus, a separate power supply for dummy platingcan be eliminated, and the number of power supplies can be reduced. Thesingle power supply may be configured to automatically switchapplication of the voltage so as to perform the actual plating processafter completion of the dummy plating process.

The plating apparatus may include a plating solution management unitconfigured to manage components of the plating solution to be suppliedto the plating unit. The plating solution management unit canautomatically perform analysis of components in the plating solution andaddition of components which have been insufficient to the platingsolution, which have heretofore been performed by hand.

Thus, the plating solution management unit can maintain each componentin the plating solution within a predetermined range. Since a platingprocess is performed with a plating solution thus managed, it ispossible to maintain good properties (components), good appearance, andgood uniformity of the thickness of a plated film formed on thesubstrate. The plating solution management unit may be provided insideor outside of the frame of the plating apparatus.

The plating solution management unit may be configured to analyze and/orestimate components of the plating solution and to add an insufficientcomponent to the plating solution through a feedback control and/or afeedforward control. For example, the plating solution management unitextracts a portion of the plating solution as a sample from the platingtank and analyzes it. Components which have been insufficient for apredetermined amount are added into the plating solution through afeedback control based on the analysis by the plating solutionmanagement unit, a feedforward control estimating disturbances includingthe plating time or the number of plated substrates, or a combination ofthe feedback control and the feedforward control. Thus, each componentin the plating solution can be maintained within a predetermined range.

The plating apparatus may include a communication device configured tocommunicate information through a communication network using acomputer. The communication device can transmits information on, forexample, plating results to proper units or devices through thecommunication network using the computer. Thus, required information ismutually transmitted through the communication device so as to controlthe units or devices based on the information to achieve a fullyautomatic plating process. The communication device may be providedinside or outside of the frame of the plating apparatus.

The plating apparatus may include a resist stripping unit configured tostrip and remove the resist used as a mask from the surface of the seedlayer formed on the substrate. The resist stripping unit may be providedinside or outside of the frame of the plating apparatus. From aviewpoint of continuous processing, it is desirable that the resiststripping unit should strip a resist on a substrate while the substrateis held by a substrate holder. The substrate after stripping the resistmay be returned to a substrate cassette.

The plating apparatus may include a seed layer removal unit configuredto remove an unnecessary portion of a seed layer formed on thesubstrate. The seed layer removal unit may be provided inside or outsideof the frame of the plating apparatus. From a viewpoint of continuousprocessing, it is desirable that the seed layer removal unit shouldremove an unnecessary portion of a seed layer on a substrate while thesubstrate is held by a substrate holder. The substrate after removingthe seed layer may be returned to a substrate cassette.

The plating apparatus may include an annealing unit configured to annealthe plated film formed on the surface of the substrate. The annealingunit may be provided inside or outside of the frame of the platingapparatus.

The plating apparatus may include a reflowing unit configured to reflowthe plated film formed on the surface of the substrate. The reflowingunit may be provided inside or outside of the frame of the platingapparatus.

The plating apparatus may include a neutralization unit configured toperform a neutralization treatment on the surface of the substrate.After the substrate has been plated and cleaned, acid or alkalicomponents contained in the plating solution may remain on thesubstrate. With the neutralization unit, since neutralization treatmentis performed on the substrate after the plating process, it is possibleto eliminate adverse influence on the resist stripping process and theseed layer removal process, which are performed after the platingprocess, from acid or alkali. For example, the neutralization treatmentsolution may comprise an alkalescent solution containing trisodiumphosphate. The neutralization unit may be provided inside or outside ofthe frame of the plating apparatus.

The plating apparatus may include a visual inspection unit configured toinspect an appearance of the plated film formed on the surface of thesubstrate. Some substrate may have a defective appearance of a platedfilm for various reasons including anomaly of a plating solution, asubstrate, and a plating apparatus. If a plating process is continuedwithout halting the plating apparatus when a defective substrate isproduced, then the number of defective substrates is increased. Thevisual inspection unit performs visual inspection of the plated film andnotifies an operator when the plated film has a defective appearance. Atthat time, the plating apparatus is halted, and the defective substrateis recorded in substrate processing data. Thus, the number of defectivesubstrates can be reduced, and the defective substrates can be removedbased on the substrate processing data. The visual inspection unit maybe provided inside or outside of the frame of the plating apparatus. Thevisual inspection unit may be configured to inspect the appearance ofthe plated film in a contact or non-contact manner.

The plating apparatus may include a film thickness measurement unitconfigured to measure film thickness of the plated film formed on thesurface of the substrate. The film thickness of a plated film formed ona substrate may vary according to influence from patterns formed on asubstrate and conditions of the apparatus, the plating solution, and thesubstrate. In some cases, the within wafer uniformity of the filmthickness of the plated film may excessively be lowered so as not tomeet the specification limits. If the plating apparatus is operated toplate substrates continuously, then the number of defective substratemay be increased. Even if the within wafer uniformity of the filmthickness is within the specification limits, a subsequent polishingprocess may be required according to the plating process. In such acase, it is necessary to set the amount of polishing to be required. Thefilm thickness measurement unit may be configured to measure adistribution of the film thickness of the plated film formed on thesubstrate over an overall surface of the substrate. Based on themeasurement results, the film thickness measurement unit determineswhether or not the substrate has good quality. If the substrate does nothave good quality, the substrate is recorded in substrate processingdata. Based on a rate of defective substrates recorded in the substrateprocessing data, the plating apparatus is halted, and an operator isnotified of the anomaly. Thus, defective substrates, which have a lowwithin wafer uniformity of the film thickness of the plated film, can beremoved, and the required amount of the plated film to be polished canbe set in a case where there is a polishing process as a subsequentprocess. The film thickness measurement unit may be provided inside oroutside of the frame of the plating apparatus. The film thicknessmeasurement unit may be configured to measure the film thickness of theplated film in a contact or non-contact manner.

The plating apparatus may include a plating area measurement unitconfigured to measure an actual area in which the plated film is to beformed on the surface of the substrate. A plating area is required todetermine plating conditions. However, a plating area cannot be known orotherwise cannot accurately be known in some cases. The plating areameasurement unit can measure an actual area (plating area) in which aplated film is to be formed. Thus, a current value which determinesplating conditions can be accurately determined. Accordingly, it ispossible to accurately obtain a plated film having a predetermined filmthickness in a predetermined plating time. In particular, in a casewhere a single substrate is plated at a time, substrates havingdifferent plating areas can be plated so as to have a predetermined filmthickness merely by setting a current density and a plating period oftime. Accordingly, setting of recipes is greatly facilitated.

The plating area measurement unit may be provided inside or outside ofthe frame of the plating apparatus. The plating area measurement unitmay be configured to supply a current to the substrate to measure theactual area. The plating area measurement unit may be configured tooptically scan the surface of the substrate to measure the actual area.For example, when a substrate is sealed at a peripheral portion anddetachably held by a substrate holder in a state such that a surface ofa substrate to be plated is exposed externally, the surface of thesubstrate is optically scanned to measure a plating area.

The plating apparatus may include a polishing unit configured to polisha surface of the plated film to adjust film thickness of the platedfilm. The polishing unit may be provided inside or outside of the frameof the plating apparatus. The polishing unit may be configured toperform chemical mechanical polishing or mechanical polishing to polishthe surface of the plated film.

The plating apparatus may include a chemical liquid adjustment unitconfigured to remove metal impurities or organic impurities mixed in theplating solution or generated decomposition products. In order tomaintain evaluation properties of a deposited film, a plating solutionused in a plating process should be renewed periodically according tolevels of impurities mixed in the plating solution or accumulateddecomposition products. An old plating solution is discarded except forparticular plating solutions such as a gold plating solution, therebycausing loads on cost and environment. The chemical liquid adjustmentunit can remove impurities and decomposition products contained in anold plating solution so as to lengthen a frequency of renewal of aplating solution. Thus, it is possible to reduce loads on cost andenvironment. The chemical liquid adjustment unit may be provided insideor outside of the frame of the plating apparatus. The chemical liquidadjustment unit may include at least one of an electrolytic processsection, an ion exchange section, an activated carbon process section,and a coagulation and settlement section.

The plating apparatus may include a chemical liquid supply and recoveryunit configured to supply a chemical liquid to the plating tank andrecover the chemical liquid from the plating tank. With the chemicalliquid supply and recovery unit, a highly corrosive or harmful chemicalliquid which would exert an adverse influence not only on the apparatusor units but also on human bodies can readily be handled with safebecause operators are not required to handle the chemical liquid sooften. The chemical liquid supply and recovery unit may be providedinside or outside of the frame of the plating apparatus.

The chemical liquid supply and recovery unit may include a chemicalliquid container attached in a replaceable manner. The chemical liquidsupply and recovery unit is configured to supply the chemical liquidfrom the chemical liquid container to the plating tank and to recoverthe chemical liquid from the plating tank to the chemical liquidcontainer. A commercially available chemical liquid tank or bottle maybe used as a chemical liquid container and attached in a replaceablemanner. Thus, a chemical liquid is supplied directly from the availablechemical liquid tank or bottle to the plating tank and recovered fromthe plating tank directly to the available chemical liquid tank orbottle. When the chemical liquid tank or bottle becomes empty at thetime of supply of the chemical liquid, an operator is notified of asignal indicating that the chemical liquid tank or bottle should bereplenished or replaced with a filled chemical liquid tank or bottle. Atthat time, the supply of the chemical liquid is interrupted. After thechemical liquid tank or bottle has been replenished or replaced with afilled chemical liquid tank or bottle, the supply of the chemical liquidis restarted. When the chemical liquid tank or bottle becomes full atthe time of recovery of the chemical liquid, an operator is notified ofa signal indicating that the chemical liquid tank or bottle should bereplaced with an empty chemical liquid tank or bottle or the chemicalliquid should be discharged from the chemical liquid tank or bottle. Atthat time, the recovery of the chemical liquid is interrupted. After thechemical liquid tank or bottle has been replaced with an empty chemicalliquid tank or bottle or become empty, the recovery of the chemicalliquid is restarted.

The plating apparatus may include a plating solution regeneration unitconfigured to remove an organic substance contained in the platingsolution to regenerate the plating solution. During the plating process,for example, a plating solution in which a component ratio of anadditive such as an organic component or a surface-active agent isexcessively increased beyond a predetermined range, or a platingsolution in which an additive or a surface-active agent is decomposedbut remains as a waste product can be regenerated by the platingsolution regeneration unit without replacement of the plating solution,so that cost and work for replacement with a new plating solution canremarkably be reduced. Particularly, together with use of the platingsolution management unit, a plating solution can be regenerated tosubstantially the same degree as a new plating solution. The platingsolution regeneration unit may be provided inside or outside of theframe of the plating apparatus.

The plating solution regeneration unit may be configured to remove theorganic substance through an activated carbon filter. The platingapparatus may have a plating solution circulation system for flowing theplating solution through the plating solution regeneration unit, whichincludes a replaceable activated carbon filter, and the plating tank.With such a plating solution circulation system, the plating solutionflows through the activated carbon filter in the plating solutionregeneration unit to remove an organic substance as an additive in theplating solution and a waste product into which the organic substance isdecomposed. Thus, a plating solution from which an additive component(organic substance) is removed can be returned to the plating tank.

The plating apparatus may include an exhaust gas treatment unitconfigured to remove a harmful component from gas or mist produced inthe plating apparatus and to discharge harmless gas to an exterior ofthe plating apparatus through a duct. Generally, gas or mist produced ina plating apparatus is harmful to other apparatuses or facilities. Anexhaust duct from a plating apparatus is generally connected and joinedto a collective exhaust duct. Accordingly, an exhaust gas which has notbeen treated in the plating apparatus may react with an exhaust gas fromother apparatuses so as to exert an adverse influence on otherapparatuses or facilities. The exhaust gas treatment unit can removeharmful gas and mist from an exhaust gas and introduce the exhaust gasinto a collective exhaust duct to prevent an adverse influence on otherapparatuses or facilities. Thus, it is possible to reduce loads onremoving harmful components in other apparatuses or facilities. Theexhaust gas treatment unit may be provided inside or outside of theframe of the plating apparatus.

The exhaust gas treatment unit may be configured to remove the harmfulcomponent through a wet process with an absorption liquid, a dry processwith an absorbent, or a condensation liquefaction process by cooling.The plating tank may have a first chamber holding an acid platingsolution, a second chamber holding a cyanic plating solution, and apartition to separate the first chamber and the second chamber. Thefirst chamber may include an exhaust duct to discharge an acid gasproduced from the acid plating solution in the first chamber. The secondchamber may include an exhaust duct to discharge a cyanic gas producedfrom the cyanic plating solution in the second chamber. For example, ifa plating process with an acid plating solution and a plating processwith a cyanic plating solution are performed in the same platingapparatus, then the plating solutions or gas may be mixed to produce acyanic gas. In order to prevent such a drawback, these processes haveheretofore been performed in separate plating apparatuses. With theabove arrangement, an acid gas produced from an acid plating solutionand a cyanic gas produced from a cyanic plating solution can separatelybe discharged so as to prevent the plating solutions or gas from beingmixed to produce a cyanic gas. Thus, a plating process with an acidplating solution and a plating process with a cyanic plating solutioncan be performed continuously in the same plating apparatus. The cyanicplating solution may comprise a gold plating solution or a silverplating solution.

The plating apparatus may include a waste water regeneration unitconfigured to regenerate waste water, which has been used in anddischarged from the plating unit, to reuse at least a portion ofregenerated waste water for the plating process while discharging therest of the waste water to an exterior of the plating apparatus. Acleaning process in the plating process requires a large amount ofcleaning water. A large amount of cleaning water having high cleanlinessand treatment of waste water which has been used in the plating processimpose large loads on existing facilities. With the waste waterregeneration unit, the plating apparatus has a completely or partiallyclosed system for regenerating waste water used therein. Thus, it ispossible to reduce the amount of cleaning water having high cleanlinessand loads on waste water treatment required for the facilities. Thewaste water regeneration unit may be provided inside or outside of theframe of the plating apparatus.

The waste water regeneration unit may be configured to regenerate thewaste water by at least one of microfiltration, ultraviolet irradiation,ion exchange, ultrafiltration, and reverse osmosis. A portion or all ofcleaning water used in the plating unit can be stored in a tank of thewaste water regeneration unit and recovered therein. Then, a portion orall of the regenerated water can be used as cleaning water, and the restof the regenerated water can be discharged to the facilities or watertank.

According to a second aspect of the present invention, there is provideda plating apparatus having a loading/unloading section configured toload and unload a cassette housing substrates, a sensor provided in theloading/unloading section for detecting sizes of the substrates receivedin the cassette, and a plurality of tools corresponding to sizes ofsubstrates to be plated. The plating apparatus includes a tool stockerto store the plurality of tools and a plating section configured toperform at least a plating process. The plating apparatus also includesa controller configured to select a tool corresponding to a sizedetected by the sensor from the plurality of tools, and a transferdevice configured to hold and transfer the tool selected by thecontroller to the plating section.

If a plating apparatus is designed so as to correspond to the size of asubstrate to be plated, then a plurality of plating apparatuses arerequired to correspond various sizes of substrates. Accordingly, a largespace for installation and utilities such as a power supply are requiredin a clean room. With the above arrangement, a single plating apparatuscan perform a plating process on substrates having different sizes, sothat a required space in a clean room, which is expensive, requiredenergy, and required cost can be reduced while substrates havingdifferent sizes are plated.

According to a third aspect of the present invention, there is provideda plating apparatus having a plurality of plating tanks each having aplating solution and an anode therein. The plating apparatus includes asingle power supply configured to selectively apply a voltage between asubstrate and anodes in the plurality of plating tanks so as to performsequential plating processes.

Thus, the use of the single plating power supply can reduce the numberof plating power supplies. Accordingly, the plating apparatus can bemade compact in size. Further, when troubles occur in the plating powersupply, the plating process can be interrupted before a substrate hasbeen plated or while a substrate is plated. Accordingly, it is notnecessary to discard the substrate, and the substrate can be plated bythe plating power supply that has been repaired.

The plurality of plating tanks may contain different kinds of metals.The plating apparatus may include a sensor for detecting when asubstrate is immersed in the plating solutions of the plurality ofplating tanks, and a switch operable to switch the single power supplybased on a signal from the sensor.

According to a fourth aspect of the present invention, there is provideda plating method to form a plated film on a surface of a substrate. Aresist is applied on a surface of a seed layer formed on the substrate.After an ashing process of the resist, a hydrophilic process isperformed on the surface of the substrate to provide hydrophilicity tothe surface of the substrate. After the hydrophilic process, the surfaceof the substrate is cleaned or activated. The surface of the substrateis brought into a plating solution while the resist is used as a mask soas to perform a plating process to form a plated film on the surface ofthe substrate.

The hydrophilic process may comprise continuously performing two or moretypes of hydrophilic processes. The resist may be stripped and removedfrom the surface of the substrate after the plating process. Anunnecessary portion of a seed layer formed on the surface of thesubstrate may be removed. The plated film formed on the surface of thesubstrate may be annealed. The plated film formed on the surface of thesubstrate may be reflowed. A neutralization treatment may be performedon the surface of the substrate after the plating process. An appearanceof the plated film formed on the surface of the substrate may beinspected. Film thickness of the plated film formed on the surface ofthe substrate may be measured. An actual area in which the plated filmis to be formed on the surface of the substrate may be measured. Theplated film formed on the surface of the substrate may be polished toadjust film thickness of the plated film.

With the above arrangement, a plating solution can be introducedreliably into an opening of the resist on the surface of the substratewithout adding any surface-active agent, so that a plating processwithout any plating defects such as insufficient plating can beachieved. Further, a plated film suitable for a protruding electrodesuch as a bump can be automatically formed with a dipping-type process,which can readily release air bubbles.

According to a fifth aspect of the present invention, there is provideda plating apparatus having a plating unit configured to form a platedfilm on a surface of a substrate while a resist is applied as a mask ona surface of a seed layer formed on a substrate. The plating apparatusincludes a resist stripping unit configured to strip and remove theresist from the surface of the seed layer, and an etching unitconfigured to remove an unnecessary portion of the seed layer formed onthe surface of the substrate. The plating unit, the resist strippingunit, and the etching unit are incorporated integrally with each other.

Since the plating unit, the resist stripping unit, and the etching unitare incorporated integrally with each other, a plating process, a resistremoval process, and a seed layer removal process can be performedcontinuously. Further, the plating apparatus can flexibly perform adesired plating process.

The plating apparatus may include a cleaning unit configured to cleanthe substrate and a pre-treatment unit configured to perform apre-treatment process before plating. The plating apparatus may includea reflowing unit configured to reflow the plated film formed on thesurface of the substrate. The plated film may form a bump.

With the above arrangement, a bump formation process including a platingprocess can be performed continuously so as to reduce a space for theapparatus. Further, the plating apparatus can achieve a desired platingprocess suitable for limited production of a wide variety of goods.

The above and other objects, features, and advantages of the presentinvention will be apparent from the following description when taken inconjunction with the accompanying drawings which illustrate preferredembodiments of the present invention by way of example.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A through 1E are cross-sectional views showing a process offorming a bump (protruding electrode) on a substrate;

FIG. 2 is a schematic plan view showing a plating section in a platingapparatus according to a first embodiment of the present invention;

FIG. 3 is a plan view showing a substrate holder in the plating sectionshown in FIG. 2;

FIG. 4 is an enlarged cross-sectional view of a plating unit in theplating section shown in FIG. 2;

FIG. 5 is a plan view showing the plating apparatus including theplating section shown in FIG. 2 and other various units;

FIG. 6 is a flow chart showing a process before a substrate is removedfrom the substrate holder in the plating apparatus shown in FIG. 5;

FIG. 7 is a flow chart showing a process after the substrate is removedfrom the substrate holder in the plating apparatus shown in FIG. 5;

FIG. 8 is a schematic plan view showing a plating apparatus according toa second embodiment of the present invention; and

FIG. 9 is a schematic plan view showing a plating apparatus according toa third embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

A plating apparatus according to embodiments of the present inventionwill be described below with reference to FIGS. 1A through 9. Like orcorresponding parts are denoted by like or corresponding referencenumerals throughout drawings, and will not be described belowrepetitively.

FIG. 2 is a schematic plan view showing a plating section 1 in a platingapparatus according to a first embodiment of the present invention. Asshown in FIG. 2, the plating section 1 has a rectangular frame 2, twocassette tables 12 each for placing thereon a cassette 10 which housessubstrates such as semiconductor wafers, an aligner 14 for aligning anorientation flat or a notch of a substrate in a predetermined direction,and a cleaning and drying device 16 for cleaning a plated substrate androtating the substrate at a high speed to dry the substrate. Thecassette tables 12, the aligner 14, and the cleaning and drying device16 are disposed along the same circle in the frame 2. The platingsection 1 includes a substrate loading/unloading unit 20 disposed alonga tangent line to the circle for loading a substrate onto and unloadinga substrate from a substrate holder 18. The plating section 1 also has asubstrate transfer device (transfer robot) 22 disposed at the center ofthe circle for transferring a substrate between the cassette tables 12,the aligner 14, the cleaning and drying device 16, and the substrateloading/unloading unit 20.

The plating section 1 has a stocker 24 for storing or temporarilyreceiving substrate holders 18, a pre-wetting tank (pre-wetting section)26, a pre-soaking tank (pre-soaking section) 28, a first cleaning tank30 a for cleaning a surface of the substrate with pure water, a blowingtank 32 for removing water from a cleaned substrate, a second cleaningtank 30 b for cleaning a surface of the substrate, and a plating tank34. The stocker 24, the pre-wetting tank 26, the pre-soaking tank 28,the first cleaning tank 30 a, the blowing tank 32, the second cleaningtank 30 b, and the plating tank 34 are arranged in order from thesubstrate loading/unloading unit 20 in the frame 2. The pre-wetting tank26 is configured to immerse a substrate in pure water to providehydrophilicity to a surface of the substrate. For example, thepre-soaking tank 28 is configured to etch an oxide film, which has ahigh electrical resistance, formed on a surface of a seed layer with atreatment solution such as a sulfuric acid or hydrochloric acid solutionto remove the oxide film and clean or activate a surface of an exposedseed layer. The plating tank 34 has an overflow tank 36 and a pluralityof plating units 38 disposed within the overflow tank 36. Each of theplating units 38 is configured to hold one substrate therein to platethe substrate with copper. In the present embodiment, a copper platingprocess is performed on substrates in the plating tanks 34. However, thepresent invention is also applicable to nickel, solder, or gold plating.

In the present embodiment, the pre-wetting section comprises apre-wetting tank 26 for immersing a substrate in pure water. However,the pre-wetting section may comprise a pre-wetting device for ejectingpure water through a spray to a surface of a substrate. The pre-wettingsection is preferably substantially under vacuum or under a pressurelower than an atmospheric pressure. Alternatively, pure water to besupplied to the pre-wetting section may be deaerated by a deaerationdevice.

Further, the plating section 1 has one pre-wetting tank (pre-wettingsection) 26 in the illustrated example. However, the plating section 1may have a plurality of pre-wetting portions having differentarrangements. Specifically, the plating section 1 may have a pluralityof pre-wetting portions including a dipping-type pre-wetting portionusing deaerated water as described above, a spray-type pre-wettingportion, and the like. In such a case, a suitable pre-wetting portioncan be selected according to a recipe. With this arrangement,limitations on processes due to types of pre-wetting sections can beeliminated, and the plating apparatus can perform various types ofprocesses.

The pre-soaking tank 28 is supplied with an acid solution such as asulfuric acid or hydrochloric acid solution, ozone water, an alkalisolution, an acid degreasing agent, a solution containing a developer, asolution containing a resist stripping solution, reduced water of anelectrolytic solution, or the like. Type of solution to be used isselected according to purposes of plating. Further, a substrate may betreated with ozone water and then treated with an acid solution.Alternatively, an electrolytic process may be performed on a substratein an acid solution or an acid degreasing agent in a state such that thesubstrate serves as a cathode.

The plating section 1 also has a substrate holder transfer device(substrate transfer device) 40 disposed along the units 20, 24, 26, 28,30 a, 32, 30 b, and 34. The substrate holder transfer device 40transfers substrate holders 18 together with substrates between theunits 20, 24, 26, 28, 30 a, 32, 30 b, and 34. The substrate holdertransfer device 40 includes a first transporter 42 for transferringsubstrate holders 18 between the substrate loading/unloading unit 20 andthe stocker 24, and a second transporter 44 for transferring substrateholders 18 between the stocker 24, the pre-wetting tank 26, thepre-soaking tank 28, the cleaning tanks 30 a and 30 b, the blowing tank32, and the plating tank 34.

The plating section 1 includes a plurality of paddle driving units 46 onthe opposite side of the overflow tank 36 to the substrate holdertransfer device 40. Each of the paddle driving units 46 drives a paddle202 (see FIG. 4) provided in each plating unit 38. The paddle 202 servesas a stirring rod for agitating a plating solution.

The substrate loading/unloading unit 20 has rails 50 and a flat loadingplate 52 slidable horizontally along the rails 50. The loading plate 52supports two substrate holders 18 placed parallel to each other in ahorizontal state. A substrate is transferred between one of thesubstrate holders 18 and the substrate transfer device 22, and thenanother substrate is transferred between the other of the substrateholders 18 and the substrate transfer device 22.

FIG. 3 is a plan view showing the substrate holder 18 shown in FIG. 2.As shown in FIG. 3, each substrate holder 18 has a stationary supportmember 54 in the form of a flat rectangular plate and a movable supportmember 58 in the form of a ring. The movable support member 58 isattached to the stationary support member 54 in a state such that it canbe opened and closed via a hinge 56. A clamp ring 62 is attached to themovable support member 58 on the opposite side of the movable supportmember 58 to the stationary support member 54. The clamp ring 62 issupported by bolts 64 extending from the movable support member 58through elongated holes 62 a formed along a circumferential direction inthe clamp ring 62. Thus, the clamp ring 62 is configured to be rotatableand not to be detached from the movable support member 58.

The stationary support member 54 has L-shaped pawls 66 positioned near aperipheral portion of the movable support member 58. The pawls 66 arearranged along the circumferential direction at equal intervals. Theclamp ring 62 has a plurality of protrusions 68 projecting radiallyoutward. The protrusions 68 are formed integrally with the clamp ring 62and arranged at equal intervals. The clamp ring 62 also has slightlyelongated holes 62 b (three holes in FIG. 3) for rotating theprotrusions 68. Each protrusion 68 has an upper surface tapered so as tobe inclined along a rotating direction. Each pawl 66 has a lower surfacetapered so as to be inclined along the rotating direction and opposed tothe upper surface of the corresponding protrusion 68.

When the movable support member 58 is in an opened state, a substrate isinserted and positioned properly in a central area of the stationarysupport member 54. Then, the movable support member 58 is closed via thehinge 56. Subsequently, the clamp ring 62 is rotated clockwise so as toslide the protrusions 68 of the clamp ring 62 into the lower portions ofthe L-shaped pawls 66. Thus, the movable support member 58 is fastenedto and locked in the stationary support member 54. When the clamp ring62 is rotated counterclockwise, the protrusions 68 of the clamp ring 62are slid out from the L-shaped pawls 66 to unlock the movable supportmember 58 from the stationary support member 54.

When the movable support member 58 is locked in the stationary supportmember 54 as described above, a seal packing (not shown) provided on asurface of the movable support member 58, which faces the stationarysupport member 54, is pressed against a surface of the substrate so asto provide a reliable seal. Simultaneously, the substrate is broughtinto electric contact with an external electrode (not shown), which isprovided on the stationary support member 54, at a location sealed bythe seal packing.

The movable support member 58 is opened and closed by a cylinder (notshown) and the weight of the movable support member 58. Specifically,the stationary support member 54 has a through-hole 54 a formed therein.The loading plate 52 has a cylinder provided at a position facing thethrough-hole 54 a when the substrate holder 18 is mounted on the loadingplate 52. The movable support member 58 is opened when the movablesupport member 58 is pushed upward through the through-hole 54 a by acylinder rod (not shown). The movable support member 58 is closed by itsown weight when the cylinder rod is retracted.

In the present embodiment, the movable support member 58 is locked andunlocked by rotating the clamp ring 62. The loading plate 52 has alocking/unlocking mechanism provided on a ceiling side. Thelocking/unlocking mechanism has pins disposed at positions correspondingto the holes 62 b in the clamp ring 62 of the substrate holder 18, whichis placed on the loading plate 52 and positioned near the center of theloading plate 52. When the loading plate 52 is lifted so as to insertthe pins into the holes 62 b, the pins are rotated about the center ofthe clamp ring 62 to thereby rotate the clamp ring 62. The loading plate52 has only one locking/unlocking mechanism. After one of the twosubstrate holders 18 placed on the loading plate 52 is locked orunlocked by the locking/unlocking mechanism, the loading plate 52 isslid horizontally to lock or unlock the other of the substrate holders18.

Each of the substrate holders 18 has a sensor for detecting whether asubstrate is brought into contact with contact points when the substrateis loaded into the substrate holder 18. The sensor outputs signals to acontroller (not shown). Each of the substrate holders 18 also has a pairof hands 76 provided at ends of the stationary support member 54. Thehands 76 have substantially a T-shape and serve as support portions forsupporting the substrate holder 18 when the substrate holder 18 istransferred or suspended. Protruding ends of the hands 76 are engagedwith peripheral upper walls of the stocker 24 so that the substrateholder 18 is held in a vertically suspended state. The transporter 42 ofthe substrate holder transfer device 40 grips the hands 76 of thesubstrate holder 18 held in the vertically suspended state and transfersthe substrate holder 18. The protruding ends of the hands 76 are alsoengaged with peripheral upper walls of the pre-wetting tank 26, thepre-soaking tank 28, the cleaning tanks 30 a and 30 b, the blowing tank32, and the plating tank 34 so that the substrate holder 18 is held in avertically suspended state.

FIG. 4 shows a cross-section of one of the plating units 38. As shown inFIG. 4, the plating unit 38 has an anode 200 and a paddle (stirring rod)202. The anode 200 is disposed in the plating unit 38 at a positionfacing a surface of a substrate W when the substrate holder 18 ispositioned at a predetermined location. The paddle 202 is disposedsubstantially vertically in the plating unit 38 between the anode 200and the substrate W. The paddle 202 is configured to be movable parallelto the substrate W in a reciprocating manner by the paddle driving units46.

Thus, the paddle 202 is disposed between the substrate W and the anode200 and reciprocated parallel to the substrate W. Accordingly, a flow ofa plating solution can be equalized along the surface of the substrate Wto thereby form a uniform plated film over the entire surface of thesubstrate W.

In the present embodiment, the plating unit 38 also has a regulationplate (mask) 204 having a central hole 204 a between the paddle 202 andthe anode 200. The size of the central hole 204 a corresponds to thesize of the substrate W. The regulation plate 204 lowers electricpotentials of peripheral portions of the substrate W so as to equalizethe thickness of the plated film.

The anode 200 is held by an anode holder 206. The anode holder 206 hasan upper end which is held on peripheral upper walls of the plating unit38 in a suspended state. The plating unit 38 has a suspension portion212, which is shown by an imaginary line in FIG. 4, provided at theperipheral upper walls of the plating unit 38. A load cell 208 isattached as an anode weight measuring device to the suspension portion212. The weight of the anode 200 is measured together with the anodeholder 206 by the load cell 208.

Thus, the weight of the anode 200 can be measured directly by the loadcell 208. Accordingly, consumption of the anode 200 can be measured moreaccurately than in a case where the weight of the anode 200 hasheretofore been estimated indirectly based on the amount of currentsupplied to the anode 200. Therefore, it is possible to accuratelydetermine when the anode 200 should be replaced. The weight of the anode200 can be measured even during a plating process. Thus, even during acontinuous plating process, it is possible to accurately determine whenthe anode 200 should be replaced. Accordingly, the plating apparatus canbe operated premeditatedly.

The plating unit 38 includes a power supply 210 for applying a voltagebetween the anode 200 and the substrate W. The anode 200 is connected toan anode of the power supply 210. The seed layer 500 (see FIG. 1A) ofthe substrate W held by the substrate holder 18 is connected through thesubstrate holder 18 to a cathode of the power supply 210. The powersupply 210 also serves to apply a voltage between a dummy anode (notshown) provided in the plating tank 34 and a cathode so as to perform adummy plating process, for example, during the time of replacement of aplating solution. Specifically, the power supply 210 applies a voltagebetween the anode 200 and the seed layer 500 of the substrate W andchanges application of the voltage so as to apply a voltage between thedummy anode and the cathode for performing a dummy plating process.

Generally, a power supply which is used for dummy plating at the time ofreplacement of a plating solution is not used during an actual platingprocess. Thus, a power supply for dummy plating is not used for a longterm and is provided uneconomically. In the present embodiment, a singlepower supply 210 can be switched so as to perform a dummy platingprocess and an actual plating process. Thus, a power supply for dummyplating can be eliminated, and the number of power supplies can bereduced.

In order to facilitate switching of the power supply 210, the powersupply 210 should preferably be automatically switched so as to performan actual plating process after completion of the dummy plating process.

FIG. 5 is a plan view showing a plating apparatus including the platingsection 1 shown in FIG. 2 and other various units. Although FIG. 5 showsthat the various units are provided outside of the frame 2 of theplating section 1, the various units may be provided within the frame 2of the plating section 1. A portion or all of the various units may bedisposed outside of the frame 2 of the plating section 1.

The plating apparatus includes an ashing unit 300 for performing anashing process on a resist 502 applied on a surface of a seed layer 500of a substrate (see FIG. 1A). The ashing unit 300 is configured to applyhigh-energy light or electromagnetic waves including plasma, ultravioletrays, and far ultraviolet rays. Accordingly, high-energy ions, photons,or electrons collide with the resist 502 to produce an active gas, whichabstracts hydrogen from organic substances in the resist 502 or cutsprincipal chains or side chains of organic substances in the resist 502.Thus, the ashing unit 300 performs an ashing process on a surface of theresist 502.

When a substrate is plated while a resist is used as a mask, because theresist makes a surface of the substrate hydrophobic, the surface of thesubstrate is unlikely to be brought into contact with a plating solutionto thus cause plating defects such as insufficient plating. In thepresent embodiment, the ashing unit 300 performs an ashing process onthe resist 502 applied on the surface of the substrate prior to theplating process. The ashing process can reform a hydrophobic surface ofthe resist 502 into a hydrophilic surface. Thus, the surface of thesubstrate becomes likely to be brought into contact with a platingsolution. Further, a hydrophilic process may be performed on the surfaceof the substrate in the pre-wetting tank 26 after the ashing process toreplace a gas in the openings 502 a formed in the resist 502 (see FIG.1A) with water and further replace the water with a plating solution.Thus, it is pos Bible to prevent plating defects such as insufficientplating.

The plating apparatus also includes a plating solution management unit302 for managing components of a plating solution to be supplied to theplating tank 34. The plating solution management unit 302 extracts aportion of a plating solution as a sample from the plating tank andanalyzes it. Components which have been insufficient for a predeterminedamount are added into the plating solution through a feedback controlbased on the analysis by the plating solution management unit 302, afeedforward control estimating disturbances including the plating timeor the number of plated substrates, or a combination of the feedbackcontrol and the feedforward control. Thus, each component in the platingsolution can be maintained within a predetermined range.

The plating solution management unit 302 can automatically performanalysis of components in the plating solution and addition ofcomponents which have been insufficient to the plating solution, whichhave heretofore been performed by hand. Thus, the plating solutionmanagement unit 302 can maintain each component in the plating solutionwithin a predetermined range. Since a plating process is performed witha plating solution thus managed, it is possible to maintain goodproperties (components), good appearance, and good uniformity of thethickness of a plated film formed on the substrate.

The plating apparatus includes a communication device 304 forcommunicating information through a communication network using acomputer. The communication device 304 transmits information on platingresults or the like to proper units or devices through a communicationnetwork interconnecting the units or devices in the plating section 1,the ashing unit 300, the plating solution management unit 302, and theother units shown in FIG. 5. Thus, required information is mutuallytransmitted through the communication device 304 so as to control theunits or devices based on the information to achieve a fully automaticplating process.

The plating apparatus also includes a resist stripping unit 306, a seedlayer removal unit 308, an annealing unit 310, and a reflowing unit 312.The resist stripping unit 306 immerses the resist 502 formed as a maskon the substrate in a solvent, such as acetone, having a temperature of,for example, 50 to 60° C. to strip and remove the resist 502 after theplating process. The seed layer removal unit 308 removes portions of theseed layer 500 (see FIG. 1C), which have been unnecessary after theplating process, formed on a surface of the substrate. The annealingunit 310 anneals the plated film 504 (see FIG. 1D) formed on the surfaceof the substrate. The reflowing unit 312 reflows the plated film 504formed on the surface of the substrate.

In the present embodiment, the plating apparatus has the annealing unit310 and the reflowing unit 312. The plated film 504 is reflowed by thereflowing unit 312 to form a bump 506 (see FIG. 1E), which is rounded bysurface tension. Alternatively, the plated film 504 is annealed, forexample, at 100° C. or more by the annealing unit 310 to remove residualstress in the bump 506. The reflowing and annealing may simultaneouslyor individually be performed by a heat treatment unit.

From a viewpoint of continuous processing, it is desirable that theresist stripping unit 306 should strip a resist on a substrate while thesubstrate is held by a substrate holder, and that the seed layer removalunit 308 should remove unnecessary portions of a seed layer on asubstrate while the substrate is held by a substrate holder. Thesubstrate after stripping the resist or the substrate after removing theseed layer may be returned to a substrate cassette.

The plating apparatus includes a neutralization unit 314 having aneutralization tank for performing a neutralization treatment on asurface of a substrate immediately after the plating process. Theneutralization unit (neutralization tank) 314 is configured to immerse asubstrate, which has been plated and cleaned with water, in aneutralization treatment solution to perform neutralization treatment onthe substrate. The neutralization treatment solution is set to beacescent or alkalescent so as to have characteristics opposite to theplating solution.

After the substrate has been plated and cleaned, acid or alkalicomponents contained in the plating solution may remain on thesubstrate. According to the present embodiment, since the neutralizationtreatment is performed on the substrate immediate after the platingprocess, it is possible to eliminate adverse influence on the resiststripping process and the seed layer removal process, which areperformed after the plating process, from acid or alkali. For example,the neutralization treatment solution may comprise an alkalescentsolution containing trisodium phosphate.

The plating apparatus also includes a visual inspection unit 316 forinspecting an appearance of a plated film 504 formed on a surface of asubstrate in a contact or non-contact manner. The visual inspection unit316 performs visual inspection of the plated film 504 and notifies anoperator through the communication device 304 when the plated film 504has a defective appearance. At that time, the plating apparatus ishalted, and the defective substrate is recorded in substrate processingdata. Thus, the number of defective substrates can be reduced, and thedefective substrates can be removed based on the substrate processingdata.

Some substrate may have a defective appearance of a plated film 504 forvarious reasons including anomaly of a plating solution, a substrate,and a plating apparatus. If a plating process is continued withouthalting the plating apparatus when a defective substrate is produced,then the number of defective substrates is increased. The platingapparatus in the present embodiment can prevent such drawbacks.

The plating apparatus includes a film thickness measurement unit 318 formeasuring the film thickness of a plated film 504 formed on a surface ofa substrate in a contact or non-contact manner. The film thicknessmeasurement unit 318 is configured to measure a distribution of the filmthickness of the plated film 504 formed on the substrate over an overallsurface of the substrate. Based on the measurement results, the filmthickness measurement unit 318 determines whether or not the substratehas good quality. If the substrate does not have good quality, thesubstrate is recorded in substrate processing data. Based on a rate ofdefective substrates recorded in the substrate processing data, theplating apparatus is halted, and an operator is notified of the anomalythrough the communication device 304.

The film thickness of a plated film formed on a substrate may varyaccording to influence from patterns formed on a substrate andconditions of the apparatus, the plating solution, and the substrate. Insome cases, the within wafer uniformity of the film thickness of theplated film may excessively be lowered so as not to meet thespecification limits. If the plating apparatus is operated to platesubstrates continuously, then the number of defective substrate may beincreased. Even if the within wafer uniformity of the film thickness iswithin the specification limits, a subsequent polishing process may berequired according to the plating process. In such a case, it isnecessary to set the amount of polishing to be required. In the presentembodiment, the film thickness measurement unit 318 measures the filmthickness of the plated film 504 so as to remove defective substrates,which has a low within wafer uniformity of the film thickness of theplated film, and to set the required amount of the plated film to bepolished in a polishing unit 322.

The plating apparatus includes a plating area measurement unit 320 formeasuring an actual area in which a plated film 504 is to be formed. Themeasurement is performed before the plating process by, for example,supplying a current to the substrate. A plating area is required todetermine plating conditions. However, a plating area cannot be known orotherwise cannot accurately be known in some cases. In the presentembodiment, an actual area (plating area) in which a plated film 504 isto be formed is measured before the plating process. Thus, a currentvalue which determines plating conditions can be accurately determined.Accordingly, it is possible to accurately obtain a plated film having apredetermined film thickness in a predetermined plating time. Inparticular, in a case where a single substrate is plated at a time,substrates having different plating areas can be plated so as to have apredetermined film thickness merely by setting a current density and aplating period of time. Accordingly, setting of recipes is greatlyfacilitated.

The plating area measurement unit may comprise a measurement device foroptically scan a surface of a substrate before the plating process tomeasure a plating area. For example, a substrate is sealed at aperipheral portion and detachably held by a substrate holder in a statesuch that a surface of a substrate to be plated is exposed externally.In such a case, when the surface of the substrate is optically scanned,a plating area can be measured readily and quickly.

The plating apparatus also includes a polishing unit 322 for polishing asurface of the plated film 504 (see FIG. 1E) of the substrate bychemical mechanical polishing (CMP) or mechanical polishing (MP) toadjust the film thickness of the plated film 504.

The plating apparatus includes a chemical liquid supply and recoveryunit 324 for supplying a chemical liquid to the plating tank 34 andrecovering the chemical liquid from the plating tank 34. Thus, thechemical liquid supply and recovery unit 324 supplies a chemical liquidto the plating tank 34 and recovers the chemical liquid from the platingtank 34. Accordingly, a highly corrosive or harmful chemical liquidwhich would exert an adverse influence not only on the apparatus orunits but also on human bodies can readily be handled with safe becauseoperators are not required to handle the chemical liquid so often.

The chemical liquid supply and recovery unit 324 is configured to supplya chemical liquid from a chemical liquid container, which is attached ina replaceable manner, to the plating tank 34 and to recover the chemicalliquid from the plating tank 34 to the chemical liquid container.Specifically, a commercially available chemical liquid tank or bottlemay be used as a chemical liquid container and attached in a replaceablemanner. Thus, a chemical liquid is supplied directly from the availablechemical liquid tank or bottle to the plating tank 34 and recovered fromthe plating tank 34 directly to the available chemical liquid tank orbottle.

When the chemical liquid tank or bottle becomes empty at the time ofsupply of the chemical liquid, an operator is notified, through thecommunication device 304, of a signal indicating that the chemicalliquid tank or bottle should be replenished or replaced with a filledchemical liquid tank or bottle. At that time, the supply of the chemicalliquid is interrupted. After the chemical liquid tank or bottle has beenreplenished or replaced with a filled chemical liquid tank or bottle,the supply of the chemical liquid is restarted.

When the chemical liquid tank or bottle becomes full at the time ofrecovery of the chemical liquid, an operator is notified, through thecommunication device 304, of a signal indicating that the chemicalliquid tank or bottle should be replaced with an empty chemical liquidtank or bottle or the chemical liquid should be discharged from thechemical liquid tank or bottle. At that time, the recovery of thechemical liquid is interrupted. After the chemical liquid tank or bottlehas been replaced with an empty chemical liquid tank or bottle or becomeempty, the recovery of the chemical liquid is restarted.

The plating apparatus includes a plating solution regeneration unit 326for removing organic substances contained in a plating solution throughan activated carbon filter to regenerate the plating solution. Theplating apparatus has a plating solution circulation system (not shown)for flowing a plating solution through the plating solution regenerationunit 326, which includes a replaceable activated carbon filter, and theplating tank 34. With such a plating solution circulation system, theplating solution flows through the activated carbon filter in theplating solution regeneration unit 326 to remove organic substances asadditives in the plating solution. Thus, a plating solution from whichadditive components (organic substances) are removed can be returned tothe plating tank 34.

During the plating process, for example, a plating solution in which acomponent ratio of an additive such as an organic component or asurface-active agent is excessively increased beyond a predeterminedrange, or a plating solution in which an additive or a surface-activeagent is decomposed but remains as a waste product can be regenerated bythe plating solution regeneration unit 326 without replacement of theplating solution, so that cost and work for replacement with a newplating solution can remarkably be reduced. Particularly, together withuse of the plating solution management unit 302, a plating solution canbe regenerated to substantially the same degree as a new platingsolution.

The plating apparatus includes an exhaust gas treatment unit 328 forremoving harmful components from gas or mist produced in the platingapparatus and discharging harmless gas to an exterior of the apparatusthrough a duct. For example, the exhaust gas treatment unit 328 removesharmful components through a wet process with an absorption liquid, adry process with an absorbent, or a condensation liquefaction process bycooling.

Generally, gas or mist produced in a plating apparatus is harmful toother apparatuses or facilities. An exhaust duct from a platingapparatus is generally connected and joined to a collective exhaustduct. Accordingly, an exhaust gas which has not been treated in theplating apparatus may react with an exhaust gas from other apparatusesso as to exert an adverse influence on other apparatuses or facilities.In the present embodiment, an exhaust gas from which harmful gas andmist have been removed by the exhaust gas treatment unit 328 isintroduced into a collective exhaust duct to prevent an adverseinfluence on other apparatuses or facilities. Thus, it is possible toreduce loads on removing harmful components in other apparatuses orfacilities.

In a case of a combination of a plating process with an acid platingsolution and a plating process with a cyanic plating solution, theplating tank should preferably have a first chamber holding an acidplating solution and a second chamber holding a cyanic plating solutionwhich are separated by a partition. It is desirable that the firstchamber includes an exhaust duct to discharge an acid gas produced fromthe acid plating solution, and that the second chamber includes anexhaust duct to discharge a cyanic gas produced from the cyanic platingsolution.

For example, if a plating process with an acid plating solution and aplating process with a cyanic plating solution are performed in the sameplating apparatus, then the plating solutions or gas may be mixed toproduce a cyanic gas. In order to prevent such a drawback, theseprocesses have heretofore been performed in separate platingapparatuses. In the present embodiment, an acid gas produced from anacid plating solution and a cyanic gas produced from a cyanic platingsolution can separately be discharged so as to prevent the platingsolutions or gas from being mixed to produce a cyanic gas. Thus, aplating process with an acid plating solution and a plating process witha cyanic plating solution can be performed continuously in the sameplating apparatus. The cyanic plating solution may comprise a goldplating solution or a silver plating solution.

The plating apparatus includes a waste water regeneration unit 330 forregenerating waste water, which has been used in and discharged from theplating process, to reuse a portion or all of regenerated waste waterfor the plating process while discharging the rest of the waste water toan exterior of the apparatus.

A cleaning process in the plating process requires a large amount ofcleaning water. A large amount of cleaning water having high cleanlinessand treatment of waste water which has been used in the plating processimpose large loads on existing facilities. In the present embodiment,the plating apparatus has a completely or partially closed system forregenerating waste water used therein. Thus, it is possible to reducethe amount of cleaning water having high cleanliness and loads on wastewater treatment required for the facilities. The waste waterregeneration unit may be configured to regenerate the waste water by atleast one of microfiltration, ultraviolet irradiation, ion exchange,ultrafiltration, and reverse osmosis.

The plating apparatus includes a chemical liquid adjustment unit 332 forremoving metal impurities or organic impurities mixed in a platingsolution or generated decomposition products. The chemical liquidadjustment unit 332 includes at least one of an electrolytic processsection, an ion exchange section, an activated carbon process section,and a coagulation and settlement section.

In order to maintain evaluation properties of a deposited film, aplating solution used in a plating process should be renewedperiodically according to levels of impurities mixed in the platingsolution or accumulated decomposition products. An old plating solutionis discarded except for particular plating solutions such as a goldplating solution, thereby causing loads on cost and environment. In thepresent embodiment, impurities and decomposition products contained inan old plating solution can be removed by the chemical liquid adjustmentunit 332 so as to lengthen a frequency of renewal of a plating solution.Thus, it is possible to reduce loads on cost and environment.

A bump plating process using the plating apparatus will be describedbelow with reference to FIGS. 6 and 7. First, a seed layer 500 isdeposited as a feeding layer on a surface of a substrate as shown inFIG. 1A. Then, a resist 502 is applied onto an overall surface of theseed layer 500 so as to have a height H of, for example, 20 to 120 μm.Thereafter, openings 502 a having a diameter D of about 20 to about 200μm are formed at predetermined positions in the resist 502. Substrateshaving such openings 502 a are housed in a cassette 10 in a state suchthat surfaces of the substrates to be plated face upward. The cassette10 is loaded on the cassette table 12.

The substrate transfer device 22 picks out one of substrates from thecassette 10 on the cassette table 12 and places it on the aligner 14 toalign an orientation flat or a notch of the substrate in a predetermineddirection. The substrate aligned by the aligner 14 is transferred to theashing unit 300 to provide hydrophilicity to the resist 502 on a surfaceof the substrate by an ashing process. Then, the substrate after theashing process is transferred to the substrate loading/unloading unit 20by the substrate transfer device 22.

Two substrate holders 18 stored in the stocker 24 are lifted andtransferred to the substrate loading/unloading unit 20 by thetransporter 42 of the substrate holder transfer device 40. The substrateholders 18 are turned through 90° above the substrate holder transferdevice 40 so as to be horizontally positioned. Then, the substrateholders 18 are lowered to place the two substrate holders 18simultaneously onto the loading plate 52 in the substrateloading/unloading unit 20. At that time, the cylinder is actuated toopen the movable support member 58 of the substrate holder 18 positionednear a central portion of the substrate loading/unloading unit 20.

The substrate transfer device 22 transfers the substrate and inserts itinto the substrate holder 18. Then, the cylinder is actuated in anreverse manner to close the movable support member 58. Thereafter, themovable support member 58 is locked by the locking/unlocking mechanism.After the substrate has been loaded into one of the substrate holders18, the loading plate 52 is slid horizontally so as to position theother of the substrate holders 18 at the central position of thesubstrate loading/unloading unit 20. Another substrate is loaded intothe other of the substrate holders 18 in the same manner as describedabove, and then the loading plate 52 is returned to the originalposition.

In the substrate holder 18, a surface of the substrate to be plated isexposed through an opening of the substrate holder 18. The substrate issealed at a peripheral portion thereof by a seal packing (not shown) soas to prevent a plating solution from entering the peripheral portion ofthe substrate. The substrate is electrically connected to a plurality ofelectric contacts at portions which are not brought into contact withthe plating solution. The hands 76 of the substrate holder 18 areelectrically connected to the electric contacts. The hands 76 areconnected to a power supply to supply electric power to the seed layer500 of the substrate.

Then, the two substrate holders 18 each having the substrate loaded aresimultaneously held and lifted by the transporter 42 of the substrateholder transfer device 40. The substrate holders 18 are transferred tothe stocker 24 and turned through 90° above the stocker 24 so as to bevertically positioned. Then, the substrate holders 18 are lowered sothat the substrate holders 18 are held in a suspended manner in thestocker 24 and thus temporarily received in the stocker 24. Thesubstrate transfer device 22, the substrate loading/unloading unit 20,and the transporter 42 of the substrate holder transfer device 40 repeatthe above process so as to load substrates into substrate holders 18which have been stored in the stocker 24 and hold (temporarily receive)the substrate holders 18 in a suspended manner at predeterminedpositions in the stocker 24.

The substrate holder 18 has a sensor for detecting contacting statesbetween the substrate and the electrical contacts. When the sensordetects that the substrate is insufficiently held in contact with theelectrical contacts, it outputs a signal indicating insufficient contactto a controller (not shown).

The transporter 44 of the substrate holder transfer device 40 holds twosubstrate holders 18 temporarily received in the stocker 24. The twosubstrate holders 18 are lifted and transferred to the pre-wetting tank26 by the transporter 44. Then, the two substrate holders 18 are loweredand immersed into pure water held in the pre-wetting tank 26 to wetsurfaces of the substrates with pure water for providing hydrophilicityto the surfaces of the substrates. Any liquid can be used as apre-wetting liquid in the pre-wetting tank 26 as long as it can wet asurface of a substrate and can replace air bubbles in openings of theseed layer with the liquid so as to improve hydrophilicity of thesurface of the substrate. As described above, the plating apparatus mayhave various kinds of pre-wetting portions so as to continuously performtwo or more types of pre-wetting processes in the pre-wetting portions.In such a case, the plating apparatus can achieve various types ofprocesses.

If a substrate is detected to be insufficiently held in contact with theelectrical contacts by the sensor provided in the substrate holder 18,the substrate holder 18 having the substrate loaded therein is lefttemporarily received in the stocker 24. Thus, even if a substrate isinsufficiently held in contact with electrical contacts when thesubstrate is loaded into the substrate holder 18, a plating process canbe continued without interrupting operation of the plating apparatus.Although the substrate that is insufficiently held in contact with theelectrical contacts is not plated, a substrate that has not been platedcan be removed from the cassette after the cassette is returned.

Then, the substrate holders 18 with the substrate are transferred to thepre-soaking tank 28 in the same manner as described above. Thesubstrates are immersed in a treatment solution such as a sulfuric acidor hydrochloric acid solution held in the pre-soaking tank 28 to etch anoxide film, which has a high electrical resistance, formed on thesurface of the seed layer 500 so as to expose a clean metal surface as apre-treatment process. The substrate thus pre-treated is transferred tothe plating area measurement unit 320 to measure an actual area in whicha plated film 504 is to be formed. The measurement is performed by, forexample, supplying a current to the seed layer 500 of the substrate.Then, the substrate holders 18 with the substrates are transferred tothe cleaning tank 30 a, where surfaces of the substrates are cleanedwith pure water held in the cleaning tank 30 a.

The substrate holders 18 with the cleaned substrates are transferred tothe plating tank 34 holding a plating solution and held in a suspendedmanner in each of the plating units 38. The transporter 44 of thesubstrate holder transfer device 40 repeats the above process so as totransfer substrate holders 18 with substrates to the plating units 38 inthe plating tank 34 and hold the substrate holders 18 at predeterminedpositions in a suspended manner. After all of the substrate holders 18have been held in a suspended manner, a plating voltage is appliedbetween anodes 200 and seed layers 500 of the substrates while theplating solution overflows into the overflow tank 36. Simultaneously,the paddles 202 in the plating units 38 are reciprocated parallel to thesurfaces of the substrates by the paddle driving units 46. Thus, thesurfaces of the substrates are plated. At that time, the substrateholders 18 are supported in a suspended manner at the hands 76 on upperportions of the plating units 38. Electric power is supplied from aplating power supply through hand support portions, the hands 76, andelectrical contacts to the seed layers 500 of the substrates.

The application of the plating voltage from the plating power supply,the supply of the plating solution, and the reciprocating movement ofthe paddles are stopped after the plating process has been completed.The two substrate holders 18 with the plated substrates aresimultaneously held by the transporter 44 of the substrate holdertransfer device 40 and transferred to the cleaning tank 30 b. Thesubstrate holders 18 are immersed in pure water held in the cleaningtank 30 b to clean surfaces of the substrates with pure water. Thesubstrate holders 18 with the substrates are transferred to theneutralization unit (neutralization tank) 314 and immersed into aneutralization treatment solution to perform a neutralization process.The substrates and the substrate holders 18 are cleaned with pure waterafter the neutralization process. Then, the substrate holders 18 withthe substrates are transferred to the blowing tank 32 to remove waterdroplets attached to the substrate holders 18 and the substrates byblowing air so as to dry the substrate holders 18 and the substrates.The substrate holders 18 with the dried substrates are returned to thestocker 24 and held at the predetermined positions in a suspendedmanner.

The transporter 44 of the substrate holder transfer device 40 repeatsthe above process so as to return the substrate holders 18 with theplated substrates to the stocker 24 and to hold the substrate holders 18at predetermined positions in a suspended manner.

The two substrate holders 18 with the plated substrates which have beenreturned to the stocker 24 are simultaneously held and placed on theloading plate 52 of the substrate loading/unloading unit 20 by thetransporter 42 of the substrate holder transfer device 40. At that time,a substrate holder 18 that has been temporarily received in the stocker24 because a substrate held in the substrate holder 18 is detected to beinsufficiently held in contact with electrical contacts by the sensorprovided in the substrate holder 18 is also transferred and placed onthe loading plate 52 of the substrate loading/unloading unit 20.

Then, the movable support member 58 of the substrate holder 18positioned at the central portion of the substrate loading/unloadingunit 20 is unlocked by the locking/unlocking mechanism. The cylinder isactuated to open the movable support member 58. In this state, theplated substrate in the substrate holder 18 is picked out andtransferred to the cleaning and drying device 16 by the substratetransfer device 22. In the cleaning and drying device 16, the substrateis cleaned and rotated at a high speed to spin-dry the substrate. Then,the loading plate 52 is slid horizontally. The substrate held by theother substrate holder 18 is cleaned and dried in the same manner asdescribed above.

After the loading plate 52 is returned to the original position, the twosubstrate holders 18 from which the substrates are unloaded aresimultaneously held by the transporter 42 of the substrate holdertransfer device 40 and returned to the predetermined positions in thestocker 24. Then, the two substrate holders 18 with the platedsubstrates which have been returned to the stocker 24 are simultaneouslyheld and placed on the loading plate 52 of the substrateloading/unloading unit 20 by the transporter 42 of the substrate holdertransfer device 40. Thus, the processes as described above are repeated.All of the substrates are unloaded from the substrate holders 18 withthe plated substrates which have been returned to the stocker 24 andcleaned and dried. Thus, as shown in FIG. 1B, it is possible to obtainsubstrates W having plated films 504 grown in the openings 502 a formedin the resist 502.

Next, the cleaned and dried substrate is transferred to the visualinspection unit 316 to inspect an appearance of the plated films 504formed on the surface of the substrate. The inspected substrate istransferred to the resist stripping unit 306, where the substrate isimmersed in a solvent, such as acetone, having a temperature of, forexample, 50 to 60° C. to strip and remove the resist 502 on thesubstrate as shown in FIG. 1C. Then, the substrate from which the resist502 has been removed is cleaned and dried.

The cleaned substrate is transferred to the film thickness measurementunit 318 to measure a distribution of the film thickness of the platedfilm 504. The measured substrate is transferred to the seed layerremoval unit 308, where unnecessary portions of the seed layer 500 whichare exposed are removed after the plating process. Then, the substratefrom which the unnecessary portions of the seed layer 500 are removed iscleaned and dried.

The substrate is transferred to the reflowing unit 312, which comprises,for example, a diffusion furnace, to reflow the plated films 504 so asto form bumps 506 which have been rounded due to surface tension asshown in FIG. 1E. Alternatively, the substrate may be transferred to theannealing unit 310 to anneal the substrate at a temperature of 100° C.or more so as to remove residual stress in the bumps 506. Then, thereflowed or annealed substrate is cleaned and dried.

The cleaned substrate is transferred to the polishing unit 322 to polishsurfaces of the bumps 506 (or the plated films 504) so as to adjust thefilm thickness of the substrate. The polished substrate is cleaned anddried. Then, the substrate is returned or unloaded to the cassette 10.Thus, a sequence of processes is completed.

In the present embodiment, the substrate transfer device 22 has a dryhand and a wet hand. The wet hand is used only when a plated substrateis picked out from the substrate holder 18. The dry hand is used exceptwhen a plated substrate is picked out from the substrate holder 18.Because the substrate holder 18 seals a rear face of the substrate sothat the rear face of the substrate is not brought into contact with aplating solution, it is not necessary to use a wet hand to handle thesubstrate. However, since the dry hand and the wet hand are separatelyused, even if a plating solution contaminates a substrate because of aflow of rinse water or insufficient sealing, such contamination does notcause a rear face of another substrate to be contaminated.

Bumps formed by multilayer plating include Ni—Cu-solder, Cu—Au-solder,Cu—Ni-solder, Cu—Ni—Au, Cu—Sn, Cu—Pd, Cu—Ni—Pd—Au, Cu—Ni—Pd, Ni-solder,Ni—Au, and the like. The solder may comprise high melting point solderor eutectic solder. Alternatively, bumps may be formed by Sn—Agmultilayer plating or Sn—Ag—Cu multilayer plating and reflowed to alloythe multilayer. Because such a process does not use Pb unlike aconventional Sn—Pb solder, environmental problems which would otherwisebe caused by lead can be eliminated.

As described above, the plating apparatus in the present embodiment canautomatically perform a dipping-type electroplating process on asubstrate and form plated metal films suitable for bumps on a surface ofthe substrate when the apparatus is operated after a cassette housingsubstrates is loaded on a cassette table.

In the present embodiment, while the substrate is held in a sealedmanner at a peripheral portion and a rear face by a substrate holder,the substrate is transferred together with the substrate holder forvarious processes. However, substrates may be received and transferredin a substrate transfer device having a rack. In this case, a thermallyoxidized layer (Si oxide layer), an adhesive tape film, or the like maybe applied to a rear face of a substrate to prevent the rear face of thesubstrate from being plated.

In the present embodiment, a dipping-type electroplating process isautomatically performed to form bumps on a substrate. However, ajet-type or cup-type electroplating process, in which a plating solutionis ejected upward, may automatically be performed to form bumps on asubstrate. This also holds true in the following embodiments.

FIG. 8 is a schematic plan view showing a plating apparatus according toa second embodiment of the present invention. As shown in FIG. 8, theplating apparatus has a loading/unloading section 402 for loading andunloading cassettes 400 which house substrates such as semiconductorwafers therein, a tool stocker 404 for storing a plurality of types oftools (substrate holders) which correspond to the sizes of substrates tobe plated, a transfer device 406 for transferring a substrate togetherwith a tool holding the substrate, and a plating section 408.

The loading/unloading section 402 has sensors 410 provided at cassetteholding portions on which cassettes 400 are mounted. The sensors 410detect the sizes of the substrates received in the cassettes 400 on thecassette holding portions. Further, the loading/unloading section 402has a substrate loading/unloading unit 412 disposed near the toolstocker 404 for loading a substrate onto and unloading a substrate froma tool. The substrate is transferred from the cassette 400 to thesubstrate loading/unloading unit 412 by a transfer robot (not shown).

The tool stocker 404 stores a plurality of types of tools (substrateholders) which correspond to the sizes of substrates to be plated. Thetools include a substrate holder having substantially the same structureas shown in FIG. 3 which has the same shape as shown in FIG. 3 but candetachably hold a substrate having a diameter of, for example, 200 mm or300 mm.

The plating section 408 includes a plurality of types of plating tanksto perform various plating processes. In the present embodiment, theplating tanks include a copper plating tank 414 a to perform a copperplating process, a nickel plating tank 414 b to perform a nickel platingprocess, and a gold plating tank 414 c to perform a gold platingprocess. The substrate is sequentially transferred to the plating tank414 a, 414 b, and 414 c by the transfer device 406. Thus, variousplating processes are sequentially performed to form bumps having aCu—Ni—Au multilayer. The plating tanks are not limited to the platingtanks as described above.

In the present embodiment, the plating section 408 has a single platingpower supply 416. The power supply 416 selectively supplies electricpower through a switch 418 between a substrate and anodes of the platingtanks in which the substrate is immersed, so that the substrate issequentially plated in the copper plating tank 414 a, the nickel platingtank 414 b, and the gold plating tank 414 c. The plating apparatus mayinclude a sensor (not shown) for detecting when a substrate is immersedin the plating solutions of said plurality of plating tanks In such acase, the switch 418 switches the power supply 416 based on a signalfrom the sensor.

Thus, the use of the single plating power supply 408 can reduce thenumber of plating power supplies. Accordingly, the plating apparatus canbe made compact in size. Further, when troubles occur in the platingpower supply, the plating process can be interrupted before a substratehas been plated or while a substrate is plated. Accordingly, it is notnecessary to discard the substrate, and the substrate can be plated bythe plating power supply that has been repaired.

The plating processes in the plating apparatus will be described below.First, a seed layer 500 is deposited on a surface of a substrate asshown in FIG. 1A. Then, a resist 502 is applied onto an overall surfaceof the seed layer 500. Thereafter, openings 502 a are formed atpredetermined positions in the resist 502. Substrates having suchopenings 502 a are housed in a cassette 400. The cassette 400 isintroduced into the loading/unloading section 402 and loaded on thecassette holding portion of the loading/unloading section 402. At thattime, the sensor 410 provided at the cassette holding portion detectsthe sizes of the substrates housed in the cassette 400 and sends asignal to a controller (not shown).

The controller sends the signal to the transfer device 406, whichselects a tool having a size suitable for a substrate housed in thecassette 400 introduced into the loading/unloading section 402, picksout the tool from the tool stocker 404, and transfers the tool to thesubstrate loading/unloading unit 412. A substrate is picked out from thecassette 400 by the transfer robot (not shown) and transferred to thesubstrate loading/unloading unit 412. The substrate is held by the toolin the substrate loading/unloading unit 412.

The transfer device 406 holds the substrate together with the tool andperforms a necessary process such as pretreatment on a surface of thesubstrate. Then, the transfer device 406 transfers the substrate to thecopper plating tank 414 a and immerses the substrate in a platingsolution of the copper plating tank 414 a to form plated copper films ona surface of the seed layer 500. The transfer device 406 transfers thesubstrate together with the tool to the nickel plating tank 414 b andimmerses the substrate in a plating solution of the nickel plating tank414 b to form plated nickel films on a surface of the plated copperfilm. The transfer device 406 transfers the substrate together with thetool to the gold plating tank 414 c and immerses the substrate in aplating solution of the gold plating tank 414 c to form plated goldfilms on a surface of the plated nickel film. Thus, bumps of Cu—Ni—Aualloy are formed on the surface of the substrate. The substrate on whichthe bumps are formed is returned from the substrate loading/unloadingunit 412 to the cassette 400. As with the first embodiment, necessaryprocesses such as cleaning are performed between these plating processesor after these plating processes.

If the plating apparatus is designed so as to correspond to the size ofa substrate to be plated, then a plurality of plating apparatuses arerequired to correspond various sizes of substrates. Accordingly, a largespace for installation and utilities such as a power supply are requiredin a clean room. According to the present embodiment, a single platingapparatus can perform a plating process on substrates having differentsizes, so that a required space in a clean room, which is expensive,required energy, and required cost can be reduced while substrateshaving different sizes are plated.

FIG. 9 is a schematic plan view showing a plating apparatus according toa third embodiment of the present invention. As shown in FIG. 9, theplating apparatus has one or more cassette tables 610 each for loadingand unloading a substrate cassette housing substrates such assemiconductor wafers, two cleaning units 612, two pre-treatment units614, two plating units 616, two resist stripping units 618, two etchingunits 620, and two reflowing units 622. In the illustrated example, theplating apparatus has three cassette tables 610. The cleaning units 612,the pre-treatment units 614, the plating units 616, the resist strippingunits 618, the etching units 620, and the reflowing units 622 areindependent of each other. As shown in FIG. 9, these units areincorporated integrally with each other so as to form two lines eachincluding different types of units.

The plating apparatus also has a first transfer robot 624 disposedbetween the cassette tables 610 and the cleaning units 612 fortransferring a substrate between the cassette tables 610 and thecleaning units 612, and a second transfer robot 626 disposed between thetwo lines of the units for transferring a substrate between these units.The second transfer robot 626 is movable along the lines of the units.

For example, the cleaning units 612 may immerse a substrate in purewater so as to bring a surface of the substrate into contact with purewater to clean (or rinse) the substrate and then spin-dry the substrate.For example, the pre-treatment units 614 may be configured to immerse asubstrate in a treatment solution such as a sulfuric acid orhydrochloric acid solution to etch an oxide film, which has a highelectrical resistance, formed on a surface of the substrate so as toexpose a clean metal surface. Alternatively, the pre-treatment units 614may uniformly apply a pre-treatment solution (pre-dipping solution),which constitutes a portion of a plating solution, onto a surface of asubstrate so that a plating solution is more likely to adhere to thesurface of the substrate.

For example, the plating units 616 may perform an electroplating processon openings formed in a surface of a substrate. For example, the resiststripping units 618 may be configured to strip and remove a resist filmremaining on a surface of a substrate. For example, the etching units620 may etch and remove unnecessary portions of a seed layer, which areother than bumps formed on a surface of a substrate. For example, thereflowing units 622 may be configured to heat and reflow a substrate tomelt a plated film and form hemisphere bumps on a surface of asubstrate.

The plating processes in the plating apparatus will be described below.First, a seed layer 500 is deposited as a feeding layer on a surface ofa substrate by sputtering or vapor deposition, as shown in FIG. 1A.Then, a resist 502 is applied onto an overall surface of the seed layer500 so as to have a height H of, for example, 20 to 120 μm. Thereafter,openings 502 a having a diameter D of about 20 to about 200 μm areformed at predetermined positions in the resist 502. Substrates havingsuch openings 502 a are housed in a substrate cassette. The substratecassette is loaded on the cassette table 610.

The first transfer robot 624 picks out one of substrates from thesubstrate cassette on the cassette table 610 and transfers it to one ofthe cleaning units 612 to clean a surface of the substrate with purewater. The cleaned substrate is transferred to one of the pre-treatmentunits 614 by the second transfer robot 626 to perform a pre-treatmentprocess on a substrate. In the pre-treatment unit 614, the substrate isimmersed in a treatment solution such as a sulfuric acid or hydrochloricacid solution, or a pre-treatment solution (pre-dipping solution), whichconstitutes a portion of a plating solution, is uniformly applied onto asurface of a substrate.

The pre-treated substrate is cleaned by one of the cleaning units 612 asneeded. Then, the substrate is transferred to one of the plating units616 by the second transfer robot 626 to perform an electroplatingprocess on a surface of the substrate. Thus, as shown in FIG. 1B, it ispossible to obtain a substrate W having a plated film 504 grown in theopenings 502 a formed in the resist 502.

The plated substrate W is cleaned by one of the cleaning units 612 asneeded. Then, the substrate is transferred to one of the resiststripping units 618 by the second transfer robot 626 to immerse thesubstrate in a solvent, such as acetone, having a temperature of, forexample, 50 to 60° C. to strip and remove the resist 502 on thesubstrate as shown in FIG. 1C.

The substrate from which the resist 502 has been removed is cleaned asneeded. Then, the substrate is transferred to one of the etching units620 by the second transfer robot 626 to etch and remove unnecessaryportions of a seed layer 500, which are exposed after the platingprocess, as shown in FIG. 1D.

The etched substrate is cleaned by one of the cleaning units 612 asneeded. Then, the substrate is transferred to one of the reflowing units622 by the second transfer robot 626 to heat and reflow the plated film504 of the substrate so as to form bumps rounded due to surface tensionas shown in FIG. 1E. Further, the substrate is annealed at a temperatureof 100° C. or more so as to remove residual stress in the bumps 506.

The reflowed substrate is transferred to one of the cleaning units 612by the second transfer robot 626. In the cleaning unit 612, thesubstrate is cleaned with pure water and spin-dried. The spin-driedsubstrate is returned to the substrate cassette mounted on the cassettetable 610 by the first transfer robot 624.

As described above, according to the present embodiment, a bumpformation process including a plating process can be performedcontinuously so as to reduce a space for the apparatus. Since theplating apparatus includes independent units for performing variousprocesses, the plating apparatus can flexibly achieve a desired platingprocess.

Although certain preferred embodiments of the present invention havebeen shown and described in detail, it should be understood that variouschanges and modifications may be made therein without departing from thescope of the appended claims.

INDUSTRIAL APPLICABILITY

The present invention is suitable for use in a plating apparatus forforming a bump (protruding electrode), which provides electricalconnection with an electrode of a package or a semiconductor chip, on asurface of a semiconductor wafer with use of a resist as a mask.

1-60. (canceled)
 61. A plating method comprising: ashing a resist on asurface of a seed layer on a substrate by applying at least one ofplasma, light, and an electromagnetic wave to the resist to reform ahydrophobic surface of the resist into a hydrophilic surface; andbringing the substrate into contact with a plating solution in which ananode is disposed using the resist as a mask so as to form a plated filmon the surface of the seed layer in a predetermined position whereinterconnect is formed.
 62. The plating method as recited in claim 61,further comprising: after said ashing, holding the substrate by asubstrate holder while sealing a peripheral portion of the substratewith its surface exposed.
 63. The plating method as recited in claim 62,further comprising: performing a hydrophilic process on the surface ofthe substrate held by said substrate holder after said ashing.
 64. Theplating method as recited in claim 63, wherein said hydrophilic processis performed by immersing the substrate in pure water or ejecting purewater onto the surface of the substrate.
 65. The plating method asrecited in claim 64, wherein the pure water is deaerated by a deaerationdevice.
 66. The plating method as recited in claim 63, wherein saidhydrophilic process is performed substantially under vacuum or performedunder a pressure lower than an atmospheric pressure.
 67. The platingmethod as recited in claim 63, wherein said hydrophilic processcomprises continuously performing two or more types of hydrophilicprocesses.
 68. The plating method as recited in claim 3, furthercomprising: after said hydrophilic process, bringing the surface of thesubstrate, held by said substrate holder, into contact with a treatmentsolution to clean or activate the surface of the seed layer.
 69. Theplating method as recited in claim 68, wherein the treatment solutioncomprises at least one of ozone water, an acid solution, an alkalisolution, an acid degreasing agent, a solution containing a developer, asolution containing a resist stripping solution, and reduced water of anelectrolytic solution.
 70. The plating method as recited in claim 68,wherein the treatment solution comprises an acid solution or an aciddegreasing agent so as to perform an electrolytic process on thesubstrate in the treatment solution with the substrate serving as acathode.
 71. A plating apparatus comprising: an ashing unit configuredto perform an ashing process on a resist on a surface of a seed layer ona substrate by applying at least one of plasma, light, and anelectromagnetic wave to the resist to reform a hydrophobic surface ofthe resist into a hydrophilic surface; and a plating unit configured tobring the substrate into contact with a plating solution in which ananode is disposed using the resist as a mask so as to form a plated filmon the surface of the seed layer in a predetermined position whereinterconnect is formed.
 72. The plating apparatus as recited in claim71, further comprising: a substrate holder configured to detachably holdthe substrate in a substrate loading/unloading unit after the ashingprocess while sealing a peripheral portion of the substrate with itssurface exposed.
 73. The plating apparatus as recited in claim 72,further comprising: a substrate transfer device configured to transferthe substrate between said ashing unit and said substrateloading/unloading unit.
 74. The plating apparatus as recited in claim72, further comprising: a pre-wetting section configured to perform ahydrophilic process on the surface of the substrate held by saidsubstrate holder after the ashing process.
 75. The plating apparatus asrecited in claim 74, wherein said pre-wetting section is configured toperform the hydrophilic process by immersing the substrate in pure wateror ejecting pure water onto the surface of the substrate.
 76. Theplating apparatus as recited in claim 75, further comprising: adeaeration device configured to deaerate the pure water.
 77. The platingapparatus as recited in claim 74, wherein said pre-wetting section issubstantially under vacuum or under a pressure lower than an atmosphericpressure.
 78. The plating apparatus as recited in claim 74, wherein saidpre-wetting section is comprises a plurality of pre-wetting portionshaving different functions.
 79. The plating apparatus as recited inclaim 74, further comprising: a pre-soaking section configured to bringthe surface of the substrate, held by said substrate holder, intocontact with a treatment solution after said hydrophilic process toclean or activate the surface of the seed layer.
 80. The platingapparatus as recited in claim 79, further comprising: a substrate holdertransfer device configured to transfer said substrate holder with thesubstrate held thereon between said substrate loading/unloading unit,said pre-wetting section, said pre-soaking section, and said platingunit.